This invention relates to gravity filtration methods and apparatus, and more particularly concerns gravity filtration apparatus of the continuous belt type, and continuous belt filter operations useful in industrial filtration.
The invention further relates to a method of filtering sugar cane juice.
Filtration methods and apparatus of the gravity type have been only infrequently employed in industrial filtration. Nevertheless, apparatus and method of this type have been recognized as potentially very valuable, and much preferred to the more common pressure type filters for many contexts of use. This has become especially true as the cost of traditional forms of energy has rapidly escalated.
In the last few years, modern polymers have become commonly available which are relatively inexpensive and which provide excellent results as flocculating agents. There has existed and now exists, a definite need in the art for improved gravity filtration processes and apparatus. There is a special need for such processes and apparatus which provide the user with a way to utilize the modern flocculating agents. This invention provides such apparatus and processes.
The recent patent to Kracklauer, U.S. Pat. No. 3,756,411, issued Sept. 4, 1973, provides gravity filtration apparatus of the continuous belt type. Applicant points out in that patent, that the gravity filtration systems of the prior art have suffered a number of distinct disadvantages. Gravity filtration processes would, however, be desirable and preferred for use in many instances in which they are not now used owing to the absence at the present time of a system of this type which is continuous and effective to remove solids at an economical rate.
The apparatus of the aforementioned Kracklauer patent represents a considerable improvement in the gravity filtration art especially as applied to industrial filtration processes. The continuous belt filter provided therein has certain advantages, but in some contexts of use is subject to yet further improvement.
The present invention provides apparatus of the continuous belt filter type, which is similar in many respects to the apparatus provided by Kracklauer U.S. Pat. No. 3,756,411. The apparatus and method provided herein, however, represent a distinct improvement over the aforementioned apparatus especially for use in many contexts.
More particularly, the apparatus improvements represented by the present invention are in the areas of driving the continuous belt, in removal of solid filtrate from the belt, in preventing sloughing off of solid particles from the belt into the filtrate, and in dewatering of the filter cake.
The method improvements represented by the present invention relate in the first instance to an overall method of filtration using a belt type filter.
In the second place, the method improvements relate in particular to a better method for filtering sugar cane juice in a sugar process, wherein a belt type filter of the type mentioned above is employed.
It would be desirable if filter apparatus of the continuous belt type could be provided wherein the continuous belt could be driven at a steady rate and in such a manner to avoid wrinkling or stretching of the filter belt, and to keep the belt tracking.
It would further be desirable if industrial filter apparatus of the continuous belt type could be provided wherein filter cake could be more conveniently removed from the belt, especially in a manner which would maintain the porosity of the belt.
It would especially be desirable if these features could be efficiently and economically provided in a continuous belt gravity filter which would be useful in industrial filtration operations.
It would be desirable to provide an improved filtration method useful in industrial filtration, wherein a continuous gravity filter is employed.
It would still further be desirable to provide an improved method for filtering sugar cane juice in a sugar refining process.
These desirable features, and other, are provided by the methods and apparatus of the present invention.